Neuropsychiatric and neurodevelopmental disorders in a young school-age population. Epidemiology and comorbidity in a school health perspective

Abstract

A total population of 826 7-year old children attended schools in Karlstad, a middle-sized town in central Sweden in August of 1992. Of these, 818 attended mainstream classrooms. The remaining 8, attending special schools, had been comprehensively assessed by the county habilitation team and diagnosed as having autistic disorder (n=4), Down syndrome (n=2) and cerebral palsy (n=2) with or without various comorbidities. Exactly half of the 818 children in mainstream classrooms were assigned for neuropsychiatric study in a school health setting. These 409 children were all personally examined by the author using a broad battery of instruments including teacher and parent questionnaires, teacher and parent interviews, and neurodevelop-mental and motor examination of the child. In addition, teachers evaluated motor performance, phonological and reading ability in connection with this first diagnostic assessment. The DSM-III-R was used for diagnostic classifications. Alternative diagnostic systems were used for certain categories (DAMP (Deficits in Attention, Motor control and Perception) and Asperger syndrome in particular). Follow-up measures 0.5-4 years after initial evaluation included motor examination by teachers, portions of the Illinois Test of Psycholinguistic Abilities, the Raven Coloured Matrices Test, tests of reading comprehension, Conners teacher screening and the Asperger Syndrome Screening Questionnaire (ASSQ). Screens and register searchers were also accomplished with the aim of identifying cases of autism spectrum disorders and tic disorders. Clinically severely impairing ADHD (Attention Deficit Hyperactivity Disorder) and/or DAMP, i.e. ADHD with DCD (developmental coordination disorder) was identified in 3.7% of the population. An additional 1.1% had autistic disorder or Asperger syndrome. Tourette syndrome was identified in 1.2% of the population but only in about 0.15% if attendance at a specialised clinic was required for a diagnosis to be made. Many more children were affected by DCD, mental retardation and other neurodevelopmental disorders. Boys were generally much more often affected than girls were. The rate of comorbidity was extremely high. For instance, in ADHD, more than four in five of all affected children had other clinically impairing syndromes. DAMP was a considerably stronger predictor for negative outcome than was ADHD without DCD, particularly as regards social and reading skills several years after initial assessment. The results are discussed as they relate to the need for screening, diagnosis and intervention in a school health perspective.